Corrosion-proof manner of aluminum material and sacrifice anode null for aluminum material corrosion protection

摘要

PURPOSE: To widely and excellently execute the cathodic protection of an aluminum material by using a 1st metal having lower natural potential than that of the aluminum material and capable of overvoltage corrosion-protecting and next, a 2nd metal having lower natural potential than that of the aluminum material and higher natural potential than that of the 1st metal as anodes. ;CONSTITUTION: The plate like formed sacrificial anode 10 formed by laminating a surface layer 11 composed of Mg and a rear layer 12 composed of Zn is attached, for example, to the inside wall 41 of an Al alloy (pipe line 4) to execute cathodic protection. At first, the pipe line 4 is overvoltage-protected by the action of Mg in the surface layer 11. When the surface layer 11 is vanished, Zn in the rear layer 12 acts and the potential of the pipe line 4 is suddenly increased just after switching to Zn, reaches protective potential after one month and the potential in the protectove range is kept in very wide area. Thus, after overvoltage-protection is attained by Mg, the protection by Zn is executed and the corrosion of the pipe line 4 is protected successively after the continuance of the overvoltage-protection. Furthermore, the extremely wide protective area is attained compared to a sacrificial anode composed only of Zn.;COPYRIGHT: (C)1996,JPO